Are you able to dispatch a flight with 1 or both AC packs inop?

• A. No, not permitted
• B. Yes, but always check the MEL
• C. Yes, with MEL not required
• D. Only with MEL waiver

Answer: (B)

Dispatch with one or both AC packs inop depends on what the MEL allows. The Master Minimum Equipment List specifies when an environmental control system deficiency can be deferred and under what limits, so you don’t rely on blanket rules. Saying you can proceed, but only after checking the MEL, captures the necessary process: you confirm there’s a MEL entry that permits operation with the packs inoperative and you follow any restrictions or actions it lists. If the MEL doesn’t authorize it, you must repair or defer. This reflects why consulting the MEL is essential rather than assuming it's allowed or disallowed outright.